The pedigree shows the inheritance of a genetic disorder - HSC - SSCE Biology - Question 17 - 2019 - Paper 1
Question 17
The pedigree shows the inheritance of a genetic disorder.
KEY
⚫ = Affected female
⚫ = Affected male
⚪ = Unaffected female
⭘ = Unaffected male
Which row of the tab... show full transcript
Worked Solution & Example Answer:The pedigree shows the inheritance of a genetic disorder - HSC - SSCE Biology - Question 17 - 2019 - Paper 1
Step 1
Autosomal dominant
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Answer
In autosomal dominant inheritance, at least one affected parent contributes to the probability of an offspring being affected. Given the pedigree, this inheritance pattern is evident as both affected parents have affected offspring.
Step 2
Autosomal recessive
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Answer
In autosomal recessive inheritance, two unaffected parents can have affected offspring if both are carriers of the recessive allele. In this pedigree, it is possible that unaffected parents have affected offspring, indicating that there is a chance for this mode of inheritance.
Step 3
Sex-linked dominant
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Answer
This mode suggests that the trait is associated with a dominant allele found on the X chromosome. In this pedigree, affected males have affected daughters, which supports the sex-linked dominant claim.
Step 4
Sex-linked recessive
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Answer
In sex-linked recessive inheritance, males are typically more affected than females due to having one X chromosome. The pedigree supports that affected males do not pass on the trait to sons, which aligns with this mode of inheritance.
